<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function Animal(){
            this.name='defaultName'
        }
        let obj1={a:1}
        /* let obj2=obj1
        console.log(obj1,obj2); */
        let obj2=obj1
        obj2=new Animal
        obj2=null
        // console.log(obj2);
        // obj2.a=2
        console.log(obj1);
    </script>
</body>
</html>